# Sandbox Environment

> Test safely with sandbox keys and testnet faucets.

Section: Getting Started
Source: https://coincircuit.io/docs/guides/sandbox/
Interactive version: https://coincircuit.io/api-reference?tab=guides&guide=sandbox

Run your full integration against the sandbox before going live: the same API behavior on testnet, with no real funds at stake.

## Base URLs
- **Production:** `https://api.coincircuit.io`
- **Sandbox:** `https://sandbox-api.coincircuit.io`

Use sandbox (test) API keys against the sandbox base URL. Live keys only work against production.

## Testnets
Sandbox payments settle on each blockchain's test network:
- **Tron:** Nile
- **Ethereum:** Sepolia
- **Solana:** Devnet

## Testnet faucets
Get free testnet tokens to fund sandbox payments.

### Tron (recommended)
Install the [TronLink](https://www.tronlink.org/) wallet, then claim testnet TRX and USDT from the Nile faucet at [nileex.io/join/getJoinPage](https://nileex.io/join/getJoinPage).

### Ethereum (Sepolia)
Claim Sepolia testnet ETH from the [Google Cloud faucet](https://cloud.google.com/application/web3/faucet/ethereum/sepolia).

### Solana
Claim devnet SOL from [faucet.solana.com](https://faucet.solana.com/).

## Simulate payments from the checkout page
When your integration runs against the sandbox, the checkout page shows a **Simulate payment** button in the bottom-right corner.

![A sandbox checkout session with the Simulate payment panel open, listing the available payment outcomes](https://coincircuit.io/images/guides/sandbox-simulate-payment.png)

Use it to trigger a payment outcome for the open session without moving real funds:
- **Full payment:** completes the session.
- **Underpayment:** a partial deposit, 50% of the amount.
- **Overpayment:** an excess deposit, 150% of the amount.
- **AML failure:** a deposit from a sanctioned sender that fails screening.

Enter a custom amount if you want a specific value. Select an asset and network first so the session has a deposit address to pay into.